The present invention relates generally to an apparatus and method to be utilized for the calibration of ultrasound equipment and, more particularly, to an apparatus and a method for calibrating the ultrasound equipment used to determine the velocity of flowing fluids.
Ultrasound devices are commonly used in a variety of applications. Typically, such devices can be operated in two different modes: a b-mode or a doppler mode. When operated in the b-mode, an ultrasound device can be used to evaluate certain structural dimensions and characteristics. When operated in the doppler mode, an ultrasound device can be used to evaluate the velocity of flow of a fluent medium.
A major concern in the utilization of ultrasound devices is proper calibration of the device such that measured data can be accurately interpreted. Various approaches have been attempted to provide such calibration, including comparing the signals received from an oscillator transmitting upstream in a flowing media with those received from transmitting downstream.
When making such direct comparisons, extraordinarily stringent precision is required of the various components with a corresponding capital expenditure for the necessary equipment, including certain circuit configurations, high quality operational amplifiers and precision components. Further, the accuracy and stability of the oscillators or multivibrators are very difficult to maintain.
Because of the inherent inaccuracies and expense of equipment needed to reliably calibrate ultrasound equipment, many of the significant applications of such equipment, particularly when operated in the doppler mode, have been largely neglected due to non-availability of convenient relatively inexpensive calibration techniques.